Red kangaroos are dedicated herbivores whose diet centers on grasses and forbs when the landscape is green, then shifts heavily toward shrubs when drought sets in. This flexibility is one reason the species thrives across nearly all of mainland Australia, from semi-arid scrubland to open grassland. But the diet story is richer than a simple plant list: it involves a specialized gut, self-replacing teeth, remarkable water conservation, and a competitive relationship with livestock that has shaped Australian rangeland policy for decades.
Grasses First, Shrubs When They Must
When rain has been decent and pasture is green, red kangaroos eat mostly grass and broad-leaved forbs. Studies in western New South Wales found that when those foods were readily available, red kangaroos selected them preferentially, behaving much like sheep grazing the same country.1Wildlife Research. Seasonal Changes in Diet Preferences of Free-Ranging Red Kangaroos, Euros and Sheep in Western New South Wales At moderate pasture levels, the dietary overlap between red kangaroos and sheep ran between roughly 58 and 73 percent, with grasses and forbs making up the bulk of both animals’ meals.2Australian Journal of Ecology. The dietary overlap between red kangaroos (Macropus rufus) and sheep (Ovis aries) in the arid rangelands of Australia
When the country dries out and grass becomes scarce, the diet pivots. Red kangaroos begin eating more chenopod shrubs, a group that includes various saltbush and bluebush species. These plants are tougher, saltier, and less palatable than green grass, but they persist through drought when almost everything else has withered. In one field study, red kangaroos were documented eating diets composed of more than 80 percent chenopods during dry conditions.3Journal of Zoology. Feeding biology of two functionally different foregut-fermenting mammals, the marsupial red kangaroo and the ruminant sheep: how physiological ecology can inform land management That same shift appears in the overlap data: during dry periods when pasture biomass dropped, both kangaroos and sheep ate more shrubs, and the dietary overlap between the two species fell to between about 52 and 66 percent, reflecting a partial parting of ways in food choice.2Australian Journal of Ecology. The dietary overlap between red kangaroos (Macropus rufus) and sheep (Ovis aries) in the arid rangelands of Australia
Sheep in the same situation lean heavily on flat-leaved chenopods like saltbush, while kangaroos still try to find what grass remains, supplementing with a mixture of flat- and round-leaved chenopods.1Wildlife Research. Seasonal Changes in Diet Preferences of Free-Ranging Red Kangaroos, Euros and Sheep in Western New South Wales This slight divergence matters ecologically. It means the two species are not exact copies of each other in their impact on the rangeland, even though they eat many of the same plants.
A Gut Designed for Low-Quality Forage
Red kangaroos are foregut fermenters, meaning food is broken down by microbes in a large, tube-shaped forestomach before it passes to the true stomach. That tube-shaped design turns out to be a real advantage when forage quality drops. As plants become more fibrous, animals that chew cud (ruminants like sheep and cattle) tend to hit a ceiling on how much they can eat, because the bulky, partially digested fibre fills up their multi-chambered stomach and slows the whole system down. The tubular foregut of kangaroos does not seem to hit that same wall as hard, allowing them to keep eating even when the available plants are tough and woody.4PubMed. Modelling digestive constraints in non-ruminant and ruminant foregut-fermenting mammals
This matters for survival. In the Australian rangelands, high-quality green grass is a seasonal luxury. For much of the year, and especially during drought, the only food around is fibrous, dry, and nutritionally poor. A digestive system that can keep processing large volumes of low-grade feed gives red kangaroos a buffer that ruminants lack. It is part of the reason kangaroos can persist through droughts that devastate livestock.
The microbial community doing the actual fermenting is still being studied. Researchers have identified bacteria in kangaroo scats that carry genes involved in cellulose breakdown, including species that appear to be well-equipped to digest plant cell walls.5PubMed Central. Siccibacter turicensis from Kangaroo Scats: Possible Implication in Cellulose Digestion The foregut microbiome in kangaroos is an active area of research, partly because the fermentation process in kangaroos produces less methane than the equivalent process in cattle and sheep, a detail that has attracted interest from climate scientists looking to understand why.
Teeth on a Conveyor Belt
Eating grass takes a real toll on teeth. Grass blades contain silica, which acts like fine sandpaper, grinding tooth enamel down over months and years. Most mammals deal with this by having high-crowned teeth that wear slowly, but kangaroos have gone a step further. Their molar teeth move forward in the jaw over the course of their lives, a process sometimes called molar progression or “marching molars.” As the front-most molar wears down from years of grinding, it gradually migrates to the front of the jaw, loosens, and eventually falls out. Behind it, a fresher, unworn molar has been moving into position. Think of it as a slow-motion conveyor belt of teeth, running for the animal’s entire life.
This system keeps a red kangaroo’s chewing surfaces sharp and effective for decades. Eventually, old kangaroos may be left with only a couple of functional molars. At that point, the animal’s ability to process tough forage drops off, and the loss of dental function can become a limiting factor on survival. But for the bulk of a kangaroo’s life, the system works remarkably well and is one of the clearest adaptations to a grass-heavy diet anywhere in the mammal world.
Thriving on Salty Shrubs Without Much Water
Chenopod shrubs pose a challenge beyond their toughness. They are loaded with salts, especially sodium and chloride. Any animal eating large quantities of these plants has to deal with excreting those excess minerals, and that typically requires water, which is exactly the resource in shortest supply during a drought. Red kangaroos handle this with impressively efficient kidneys. Even when eating diets composed overwhelmingly of chenopods, kangaroos in one study maintained comparatively low water turnover rates, concentrating their urine to shed the excess salt without losing much water.3Journal of Zoology. Feeding biology of two functionally different foregut-fermenting mammals, the marsupial red kangaroo and the ruminant sheep: how physiological ecology can inform land management
This is a critical piece of the dietary puzzle. The ability to switch to chenopods during drought is only useful if the animal can actually tolerate the salt load. Red kangaroos can, and they do it while keeping their water budget tighter than you might expect for a large mammal eating salty food in the desert. Sheep on the same diet tend to need more water to process the same mineral load, which partly explains why livestock and kangaroos diverge in their dietary choices as conditions worsen.
Red kangaroos also tend to graze at night, raising the question of whether they are picking up extra moisture from dew or higher plant water content after dark. Researchers tested this idea directly, measuring the water content of 15 known forage plants at different times of day in semi-arid Queensland. Of 29 day-versus-night comparisons, most plants showed either no difference or only trivially small changes. The conclusion was that nocturnal foraging in red kangaroos is unlikely to be explained by plants holding more water at night.6The Rangeland Journal. Daily changes in plant water content in western Queensland: implications for red kangaroo foraging times Heat avoidance is probably the better explanation: by feeding during cooler hours, kangaroos reduce their own water loss from thermoregulation.
Learning to Eat Plants After Leaving the Pouch
A young red kangaroo spends its first months sustained entirely by its mother’s milk. The shift to an adult herbivore diet does not happen overnight. Young-at-foot kangaroos, the stage after they have permanently left the pouch but are still nursing, gradually begin eating vegetation while continuing to drink milk. This transition period is a vulnerable window. Researchers have noted that young-at-foot red kangaroos are the age group most affected by drought, and one reason may be that their digestive systems are not yet fully equipped to handle the high-fibre feeds that adults rely on during tough times.7PubMed. How important is milk for near-weaned red kangaroos (Macropus rufus) fed different forages?
Milk during this transition likely serves as a supplemental source of energy and nitrogen, helping bridge the gap until the young kangaroo’s foregut microbiome and digestive capacity mature enough to extract sufficient nutrition from fibrous plants on their own. When drought strikes and forage quality plummets, mothers may not produce enough milk to compensate, and the young kangaroos are left trying to digest food their guts are not ready for. Drought mortality in young-at-foot kangaroos can be severe as a result.
Competing With Sheep for the Same Food
Because red kangaroos and sheep eat many of the same plants, the question of competition between the two species has been a sore point in Australian rangeland management for over a century. A large-scale experiment in arid Australia used paddocks stocked with sheep only, kangaroos only, and a mixture of both to test whether the two species actually harm each other’s condition. Competition turned out to be intermittent. It only became measurable during a semi-drought, when a surge of kangaroos moved into the study area from surrounding country, ramping up the pressure on a shrinking food supply. During that period, the mixed grazing treatment reduced sheep body weight, though wool production was not significantly affected.8Australian Journal of Ecology. Competition between red kangaroos (Macropus rufus) and sheep (Ovis aries) in the arid rangelands of Australia
Kangaroos, by contrast, were harder to pin down. They tended to favor paddocks that had been cleared of sheep, suggesting they noticed the reduced competition, but their physical condition did not measurably decline in the mixed treatment. The takeaway for graziers is that red kangaroos are tough competitors, but the competition is not constant. It flares during food shortages, exactly when livestock are already stressed. During good seasons, the two species coexist on the same pasture without obvious harm to either.
How Kangaroo Grazing Shapes the Landscape
The spread of artificial water sources across the Australian rangelands, originally installed for livestock, has had an unintended side effect on kangaroo populations. Permanent bores and dams give red kangaroos year-round access to water in country where they would otherwise have been limited by natural water availability. Data compiled across the rangelands suggest that about 95 percent of a red kangaroo population lives within roughly seven kilometers of permanent water, a broader range than sheep (about three kilometers) or cattle (about six kilometers).9Biological Conservation. Water-remoteness for grazing relief in Australian arid-lands The result has been higher kangaroo densities than would have existed before European settlement, concentrated around water infrastructure.
Those elevated densities create grazing pressure. Monitoring at a conservation property in the South Australian rangelands found that overabundant red kangaroos, combined with rainfall variability, had a negative impact on vegetation and on bird populations associated with chenopod plains. Fenced plots that excluded kangaroo grazing were the only places where perennial grasses persisted.10Ecological Management & Restoration. Kangaroo management in the South Australian rangelands: Impacts and challenges for conservation management That is a striking result: in some areas, the grasses that red kangaroos prefer to eat cannot regenerate at all unless the kangaroos are kept away.
The obvious management response would seem to be fencing off the water sources to push kangaroo numbers down. But that approach has been tested, and the results are discouraging. A drought-period experiment found that fencing artificial waterpoints failed to reduce either the density or the distribution of red kangaroos within four kilometers of the water.11Wildlife Research. Fencing artificial waterpoints failed to influence density and distribution of red kangaroos (Macropus rufus) A separate study of temporary water closures reached a similar conclusion: six to ten weeks of closing off water access produced no meaningful reduction in kangaroo grazing intensity.12The Rangeland Journal. The Effect of Temporary Closure of Watering Points on Grazing Intensity of Red and Grey Kangaroos With Related Observations on Feral Goats The problem is that so many water sources now dot the landscape that closing one simply sends kangaroos to the next. Food availability, not the location of any individual water point, appears to be what determines where kangaroos go.11Wildlife Research. Fencing artificial waterpoints failed to influence density and distribution of red kangaroos (Macropus rufus)
How Red Kangaroos Compare to Other Kangaroo Species
Australia has dozens of macropod species, and they do not all eat the same things. The red kangaroo’s strong preference for grass places it firmly in the “grazer” category, but many smaller relatives lean more toward browsing or mixed feeding. Among Pleistocene macropods studied through isotopic analysis of fossil teeth, larger species related to modern kangaroos showed a strong preference for C3 vegetation (which includes most shrubs and cool-season grasses), while some smaller species fed heavily on C4 plants (tropical and warm-season grasses).13bioRxiv. Niche partitioning and limited mobility characterise Middle Pleistocene kangaroos from eastern Australia This niche partitioning, different kangaroo species eating different types of plants, appears to have deep evolutionary roots.
Modern red kangaroos graze mostly on C4 grasses in the warm inland regions where they are most abundant, but they also eat C3 shrubs extensively during drought, as described above. Their dietary flexibility gives them a broader niche than many of their relatives. Smaller wallabies and rock-wallabies tend to be more restricted in both range and diet. The red kangaroo’s combination of large body size, efficient digestion, water-conserving kidneys, and self-renewing teeth amounts to a suite of adaptations that let it exploit the boom-and-bust cycle of Australian grasslands more completely than almost any other native herbivore on the continent.
What Red Kangaroos Do Not Eat
Despite their flexibility, red kangaroos are not indiscriminate. They show clear preferences and will pass over certain plants when better options are available. Woody browse from trees and tall shrubs rarely forms a significant part of their diet, unlike some other macropod species that are comfortable feeding on leaves and twigs above ground level. Red kangaroos are ground-level grazers, not browsers, and their body plan reflects this: they feed with their heads down across open plains rather than reaching up into shrubs or trees.
They are also not known to eat animal matter in any meaningful way. While a few marsupial species are omnivorous, red kangaroos show no inclination toward insects, eggs, or carrion. Their gut is built entirely for plant fermentation, and their molar teeth are shaped for grinding, not for tearing or crushing hard-bodied prey. In captive settings, red kangaroos are fed hay, commercial herbivore pellets, and fresh browse, with no animal protein in the diet. Occasionally, social media posts claim kangaroos eat meat, usually based on misidentified footage of other species or one-off observations that have never been replicated in controlled studies. The red kangaroo is, by every measure, a committed herbivore.